U.S. patent application number 16/251300 was filed with the patent office on 2019-08-01 for cleaning blade and image forming apparatus including cleaning blade.
This patent application is currently assigned to Konica Minolta, Inc.. The applicant listed for this patent is Konica Minolta, Inc.. Invention is credited to Noritoshi Hagimoto.
Application Number | 20190235437 16/251300 |
Document ID | / |
Family ID | 67392035 |
Filed Date | 2019-08-01 |
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United States Patent
Application |
20190235437 |
Kind Code |
A1 |
Hagimoto; Noritoshi |
August 1, 2019 |
CLEANING BLADE AND IMAGE FORMING APPARATUS INCLUDING CLEANING
BLADE
Abstract
A cleaning blade that removes a foreign matter adhering to a
rotational body includes: an abutment member; a supporting member
that supports the abutment member; and a holding member that holds
the supporting member, wherein the abutment member includes: an
abutment layer abutting on the rotational body; and an adjustment
layer that is a part other than the abutment layer, and an
elongation percentage of the adjustment layer is larger than an
elongation percentage of the abutment layer in a case where
frictional force is applied from the rotational body to the
abutment member during rotation of the rotational body.
Inventors: |
Hagimoto; Noritoshi;
(Toyohashi-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Konica Minolta, Inc. |
Tokyo |
|
JP |
|
|
Assignee: |
Konica Minolta, Inc.
Tokyo
JP
|
Family ID: |
67392035 |
Appl. No.: |
16/251300 |
Filed: |
January 18, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G03G 21/0017 20130101;
G03G 21/0029 20130101; G03G 2221/0005 20130101 |
International
Class: |
G03G 21/00 20060101
G03G021/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 1, 2018 |
JP |
2018-016344 |
Claims
1. A cleaning blade that removes a foreign matter adhering to a
rotational body, comprising: an abutment member; a supporting
member that supports the abutment member; and a holding member that
holds the supporting member, wherein the abutment member includes:
an abutment layer abutting on the rotational body; and an
adjustment layer that is a part other than the abutment layer, and
an elongation percentage of the adjustment layer is larger than an
elongation percentage of the abutment layer in a case where
frictional force is applied from the rotational body to the
abutment member during rotation of the rotational body.
2. The cleaning blade according to claim 1, wherein an integrated
value of tensile stress required to elongate the adjustment layer
from a length with an elongation percentage 0% to a length with an
elongation percentage 100% is lower than an integrated value of
tensile stress required to elongate the abutment layer from a
length with an elongation percentage 0% to a length with an
elongation percentage 100%.
3. The cleaning blade according to claim 1, wherein a 200% modulus
of the adjustment layer is lower than a 200% modulus of the
abutment layer.
4. The cleaning blade according to claim 1, wherein elongation
after fracture of the abutment layer is larger than elongation
after fracture of the adjustment layer.
5. The cleaning blade according to claim 1, wherein the abutment
layer and the adjustment layer are laminated in a predetermined
lamination direction.
6. The cleaning blade according to claim 5, wherein in a case of
defining a thickness of the abutment layer in the lamination
direction as a thickness t1 and defining a thickness of the
adjustment layer in the lamination direction as a thickness t2, the
thicknesses t1 and t2 have a relation of t1<t2.
7. The cleaning blade according to claim 5, wherein in a case of
defining a thickness that is a length of the abutment layer in the
lamination direction as a thickness t1, defining a thickness that
is a length of the adjustment layer in the lamination direction as
a thickness t2, defining a 100% modulus of the abutment layer as a
modulus M1, and defining a 100% modulus of the adjustment layer as
a modulus M2, the thicknesses t1, t2 and the moduli M1 and M2 have
a relation of (t2.times.M1)/(t1.times.M2) >3.
8. The cleaning blade according to claim 5, wherein the adjustment
layer is arranged on a side closer to the supporting member than
the abutment layer is, and the adjustment layer is bonded to the
supporting member.
9. The cleaning blade according to claim 1, wherein a Young's
modulus of the supporting member is 98 GPa or more and 206 GPa or
less.
10. The cleaning blade according to claim 1, wherein the supporting
member is constituted of a metallic leaf spring, and the holding
member is constituted of a sheet metal.
11. The cleaning blade according to claim 1, wherein a thickness of
the supporting member is larger than 0 and 100 .mu.m or less.
12. The cleaning blade according to claim 1, wherein the holding
member holds one end of the supporting member, and the abutment
member is fixed to a different end of the supporting member.
13. The cleaning blade according to claim 12, wherein the holding
member includes: a first holding member surface located on a side
where the abutment member abuts on the rotational body; and a
second holding member surface located on an opposite side of the
first holding member surface, the supporting member includes: a
first supporting member surface located on a side of a position
where the abutment member abuts on the rotational body; and a
second supporting member surface located on an opposite side of the
first supporting member surface and facing the first holding member
surface, and the abutment member is fixed to the first supporting
member surface.
14. The cleaning blade according to claim 1, wherein the adjustment
layer is fixed to the supporting member, and the abutment layer is
not fixed to the supporting member.
15. An image forming apparatus comprising: an image carrier that is
a rotational body; and a cleaning blade according to claim 1 that
removes a foreign matter adhering to the image carrier.
Description
[0001] The entire disclosure of Japanese patent Application No.
2018-016344, filed on Feb. 1, 2018, is incorporated herein by
reference in its entirety.
BACKGROUND
Technological Field
[0002] The present invention relates to a cleaning blade and an
image forming apparatus including the cleaning blade. More
specifically, the present invention relates to a cleaning blade
that removes a foreign matter adhering to a rotational body, and an
image forming apparatus including the cleaning blade.
Description of the Related art
[0003] An electrophotographic image forming apparatus includes: a
multi-function peripheral (M P) having a scanner function, a
facsimile function, a copy function, a function as a printer, a
data communication function, and a server function; a facsimile
machine; a copy machine; a printer; and the like.
[0004] An image forming apparatus generally forms an image on a
sheet by the following method. The image forming apparatus forms an
electrostatic latent image on an image carrier and develops the
electrostatic latent image using a development device to form a
toner image Next, the image forming apparatus transfers the toner
image to a sheet, and fixes the toner image onto the sheet by a
fixing device. Additionally, among image forming apparatuses, there
is an image forming apparatus that forms a toner image on a
photoreceptor, transfers the toner image to an intermediate
transfer belt by using a primary transfer roller, and secondarily
transfers, to a sheet, the toner image on the intermediate transfer
belt by using a secondary transfer roller.
[0005] The image forming apparatus is provided with a cleaning
blade that removes residual toner from the image carrier by the
blade abutting on the image carrier being rotated. Generally, the
cleaning blade is made of a polyurethane elastomer. Since the
polyurethane elastomer has an appropriate elasticity, the cleaning
blade made of the polyurethane elastomer has a good cleaning
property.
[0006] On the other hand, the cleaning blade made of the
polyurethane elastomer has problems as follows.
[0007] The cleaning blade constantly abuts on the image carrier.
When the polyurethane elastomer is degraded with time, there is a
problem in which permanent distortion (permanent set) occurs in the
cleaning blade due to force received from the image carrier, and
pressure (abutment pressure) with which the cleaning blade abuts on
the image carrier is decreased due to the permanent distortion.
Such decrease in the abutment pressure of the cleaning blade causes
cleaning failure. Additionally, in a case of setting high abutment
pressure in an initial stage of use of the cleaning blade in order
to compensate for the decrease in the abutment pressure of the
cleaning blade caused by time degradation of the polyurethane
elastomer, the high abutment pressure of the cleaning blade hinders
rotation of the image carrier and causes increase in torque
required to rotate the image carrier.
[0008] Additionally, performance of the cleaning blade made of the
polyurethane elastomer is largely changed depending on an
environment. In other words, the abutment pressure is increased and
the torque required to rotate the image carrier is increased in a
high-temperature environment, and the abutment pressure is
decreased in a low-temperature environment. Accordingly, the
abutment pressure is set at a high value such that required
abutment pressure can be ensured in the low-temperature
environment. As a result, the torque required to rotate the image
carrier is increased.
[0009] Furthermore, due to the characteristics of the polyurethane
elastomer, when an edge of the cleaning blade abutting on the image
carrier is pulled toward a downstream side in a rotational
direction of the image carrier, the cleaning blade is deformed and
the abutment pressure is increased. As a result, the torque
required to rotate the image carrier is increased.
[0010] A technique that can solve the above-described problem of
the cleaning blade made of the polyurethane elastomer is disclosed
in JP 2007-323026 A and the like. The cleaning blade disclosed in
JP 2007-323026 A includes: an elastic body which abuts on an image
carrier and is made of urethane rubber or the like; a metallic leaf
spring that supports the elastic body; and a holding metal plate
that holds the leaf spring. An end of the leaf spring protrudes
from the holding metal plate, and the elastic body is supported by
this part of the leaf spring protruding from the holding metal
plate. According to the cleaning blade of JP 2007-323026 A, since
the elastic body that abuts on the image carrier and the leaf
spring that supports the elastic body are constituted of separate
members, an optimum material can be selected as a material of the
leaf spring in the viewpoint of reducing change in performance due
to time degradation or depending on an environment.
[0011] JP 2008-122821 A, JP 2005-309383 A, JP 2014-115528 A, JP
2014-170118 A, and the like also disclose structures of cleaning
blades, respectively. JP 2008-122821 A discloses a technique of the
cleaning blade including an elastic layer formed on one face of a
metal plate, in which the elastic layer has a multilayer structure
including: a cleaning layer that abuts on an object to be cleaned;
and a backup layer other than the cleaning layer. At least one of a
Young's modulus or hardness of the backup layer is larger than a
Young's modulus or hardness of the cleaning layer.
[0012] JP 2005-309383 A discloses a cleaning device including: a
blade that removes residual toner from a surface of an image
carrier by a plate edge abutting on the surface of the image
carrier; an auxiliary member which covers a rear surface not facing
the image carrier out of front and rear surfaces of the blade, and
suppresses permanent deflection of the blade; and a supporting
member which is interposed between a main body casing and the
auxiliary member and supports the blade with respect to the main
body casing in cooperation with the auxiliary member. The
supporting member includes an elastic member at least in part, and
receives stress caused by the blade abutting on the image
carrier.
[0013] JP 2014-115528 A and JP 2014-170118 A each disclose a
cleaning device including an elastic blade. The elastic blade is an
edge layer having an end ridge part and includes, at 23.degree. C.:
an edge layer in which a 100% modulus value is 6 MPa or more; and a
backup layer in which a 100% modulus value is lower than 100%
modulus value of the edge layer.
[0014] In a cleaning blade disclosed in JP 2007-323026 A, an
elastic body is fixed to a metallic leaf spring by using a bonding
agent or the like. An interval between the leaf spring and the
elastic body can be hardly kept uniform in a longitudinal direction
of the cleaning blade (extending direction of a rotational shaft of
an image carrier), and there is unevenness in a height of the
elastic body in the longitudinal direction of the cleaning blade in
the vicinity of an end of a protruding part of the leaf spring. As
a result, a state of the cleaning blade abutting on the image
carrier becomes non-uniform in the longitudinal direction of the
cleaning blade, and the abutment pressure becomes uneven.
[0015] When the abutment pressure of the cleaning blade to the
image carrier is uneven, there are two problems as follows.
[0016] The first problem due to the unevenness in the abutment
pressure is non-uniformity in density caused by non-uniformity in
wear of the image carrier. When the abutment pressure becomes
uneven, the image carrier is seriously worn away in a region where
the abutment pressure is high, and the image carrier is worn little
in a region where the abutment pressure is low. When there is a
difference between the region with serious wear and the region with
little wear, non-uniformity in density is caused. In other words,
in a case where the image carrier is a photoreceptor, a charge
amount of the photoreceptor is varied by a thickness of a
photosensitive layer of the photoreceptor. A charging method is
different depending on a charging system, however; in a case where
the charging system of the photoreceptor is a corona charging
system, for example, negative ions accumulated on a thin part of
the photosensitive layer are few, and potential in the thin part of
the photosensitive layer is lower in potential in other parts.
Additionally, in a case where the charging system of the
photoreceptor is a proximity charging system such as roller
charging, electrostatic capacity in the thin part of the
photosensitive layer is larger than electrostatic capacity in other
parts, and the potential in the thin part of the photosensitive
layer is higher than the potential in other parts. When the
potential becomes uneven, a toner amount used for development
becomes different, and density becomes non-uniform.
[0017] The second problem caused by the unevenness in the abutment
pressure is cleaning failure. The cleaning failure is mainly caused
by decrease in the abutment pressure of the cleaning blade to the
image carrier. Normally, the abutment pressure is decreased by:
abrasion of an end of the cleaning blade due to increase in the
number of printed sheets; and permanent distortion of the cleaning
blade due to time degradation. In the cleaning blade having the
structure in which the elastic body is supported by the leaf spring
like JP 2007-323026 A, the abutment pressure in an initial stage of
use can be set low. Therefore, an abrasion speed of the end of the
cleaning blade is slower than an abrasion speed in other
structures, and permanent distortion of the cleaning blade due to
time degradation is smaller than in other structures. However, in a
case where there is unevenness in the abutment pressure, the
abutment pressure may become lower than the abutment pressure
required for cleaning in a part in the longitudinal direction of
the cleaning blade and cleaning failure occurs when the cleaning
blade is further abraded.
[0018] The unevenness in the abutment pressure is not caused only
by unevenness in a height of the cleaning blade due to bonding but
also by a fact that the metallic leaf spring and urethane rubber
are fixed in the first place. The metallic leaf spring is flexible,
but a deflection direction is only a direction in which the
abutment pressure is applied, and substantially the leaf spring has
a characteristic of a rigid body with respect to the rotational
direction of the photoreceptor. An end of the urethane rubber (on
an opposite side of the edge) is fixed to the metallic leaf spring
and substantially restrained. In this state, a pulled amount is
small. A fact of having a small pulled amount provides effects of
causing little deformation, suppressing increase in torque, and
suppressing degradation of the urethane caused by deformation of
the edge, but there is also a harmful effect in which unevenness in
the abutment pressure cannot be absorbed. For example, even in a
case where there is unevenness in the same height, when the pulled
amount is small, a proportion of unevenness in the height relative
to the pulled amount is high, and unevenness in the abutment
pressure is increased. In a cleaning blade made of only the
urethane rubber in the related art, even when there is unevenness
in a height of the urethane rubber, a pulled amount is large
because the urethane rubber is not restrained to the metallic leaf
spring, and also a proportion of unevenness in the height of the
urethane rubber relative to the pulled amount is low and unevenness
in the abutment pressure is little. Therefore, the unevenness in
the height of the elastic body in the longitudinal direction of the
cleaning blade is a problem peculiar to the cleaning blade in which
the abutment member is supported by the supporting member.
[0019] The above-described problem may occur not only in a cleaning
blade that removes a foreign matter adhering to an image carrier
but also in all of general cleaning blades that remove foreign
matters adhering to a rotational body.
SUMMARY
[0020] The present invention is made in view of the above-described
problems and an object of the present invention is to provide: a
cleaning blade that can suppress unevenness in abutment pressure
applied to a rotational body; and an image forming apparatus
including the cleaning blade.
[0021] To achieve the abovementioned object, according to an aspect
of the present invention, a cleaning blade that removes a foreign
matter adhering to a rotational body reflecting one aspect of the
present invention comprises: an abutment member; a supporting
member that supports the abutment member; and a holding member that
holds the supporting member, wherein the abutment member includes:
an abutment layer abutting on the rotational body; and an
adjustment layer that is a part other than the abutment layer, and
an elongation percentage of the adjustment layer is larger than an
elongation percentage of the abutment layer in a case where
frictional force is applied from the rotational body to the
abutment member during rotation of the rotational body
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] The advantages and features provided by one or more
embodiments of the invention will become more fully understood from
the detailed description given hereinbelow and the appended
drawings which are given by way of illustration only, and thus are
not intended as a definition of the limits of the present
invention:
[0023] FIG. 1 is a cross-sectional view illustrating a structure of
a main part of an image forming apparatus according to an
embodiment of the present invention;
[0024] FIG. 2 is a cross-sectional view illustrating a structure of
a photoreceptor cleaner according to an embodiment of the present
invention;
[0025] FIG. 3 is a top view illustrating a structure of a cleaning
blade according to an embodiment of the present invention;
[0026] FIG. 4 is an example of a cross-sectional view taken along a
line IV-IV in FIG. 3;
[0027] FIG. 5 is a cross-sectional view illustrating a structure of
a cleaning blade in a first comparative example;
[0028] FIG. 6 is a view illustrating the structure of the cleaning
blade when viewed from a direction indicated by an arrow V in FIG.
5;
[0029] FIG. 7 is a view schematically illustrating a pulled amount
of an edge of an abutment member in the cleaning blade of the first
comparative example;
[0030] FIG. 8 is a cross-sectional view illustrating a structure of
a cleaning blade in a second comparative example;
[0031] FIG. 9 is a view schematically illustrating a pulled amount
of an edge of an abutment member in a cleaning blade of a third
comparative example;
[0032] FIG. 10 is an enlarged view of the edge of the abutment
member in the cleaning blade illustrated in FIG. 9;
[0033] FIG. 11 is a view schematically illustrating a pulled amount
of the cleaning blade according to the embodiment of the present
invention;
[0034] FIG. 12 is an enlarged view of the edge of an abutment
member in the cleaning blade illustrated in FIG. 11;
[0035] FIG. 13 is a graph illustrating respective stress-strain
(SS) characteristics of an abutment layer and an adjustment layer
and elongation percentages EL1 and EL2 in a case where stress ST1
is applied in the embodiment of the present invention;
[0036] FIG. 14 is a graph illustrating the respective SS
characteristics of the abutment layer and the adjustment layer and
integrated values S1 and S2 of tensile stress required to elongate
a length with the elongation percentage 0% to a length with the
elongation percentage 100% in the embodiment of the present
invention;
[0037] FIG. 15 is a graph illustrating the respective SS
characteristics of the abutment layer and the adjustment layer and
200% moduli M11 and M12 in the embodiment of the present
invention;
[0038] FIG. 16 is a graph illustrating the respective SS
characteristics of the abutment layer and the adjustment layer and
elongation after fracture BL1 and elongation after fracture BL2 in
the embodiment of the present invention;
[0039] FIG. 17 is a table illustrating structures of Examples 1 to
5 of the present invention in a first practical example of the
present invention and Comparative Examples 1 to 5, and verification
results thereof;
[0040] FIG. 18 is a table illustrating various conditions in the
first practical example of the present invention; p FIG. 19 is a
graph illustrating a relation between a value of
(t2.times.M1)/(t1.times.M2) and a pulled amount in a second
practical example of the present invention; and
[0041] FIGS. 20A to 20D are cross-sectional views illustrating
structures of modified examples of the cleaning blade according to
the embodiment of the present invention.
DETAILED DESCRIPTION OF EMBODIMENTS
[0042] Hereinafter, one or more embodiments of the present
invention will be described with reference to the drawings.
However, the scope of the invention is not limited to the disclosed
embodiments.
[0043] In the following embodiment, a case where an image forming
apparatus mounted with a cleaning blade is an MFP will be
described. The image forming apparatus mounted with the cleaning
blade may not necessarily be the MFP but may also be a facsimile
machine, a copying machine, a printer, or the like.
[0044] [Structure of Image Forming Apparatus]
[0045] First, a structure of an image forming apparatus according
to the present embodiment will be described.
[0046] FIG. 1 is a cross-sectional view illustrating a structure of
a main part of the image forming apparatus according to an
embodiment of the present invention.
[0047] Referring to FIG. 1, the image forming apparatus in the
present embodiment is a full-color tandem type image forming
apparatus. The image forming apparatus forms an image by
transferring and fixing, to a recording medium T such as a sheet, a
toner image formed on a photoreceptor 1 by an electrophotographic
image forming process. The image forming apparatus includes the
photoreceptor 1 (an example of a rotational body and an image
carrier), a charging member 2, an exposure member 3, a development
device 4, an intermediate transfer belt 5, a primary transfer
roller 6, a photoreceptor cleaner 7, a secondary transfer roller 8,
an intermediate transfer belt cleaner 9, a fixing member 11, and
support rollers 12.
[0048] The photoreceptor 1, charging member 2, exposure member 3,
development device 4, primary transfer roller 6, and photoreceptor
cleaner 7 are provided for each of toner colors yellow (Y), magenta
(M), cyan (C), and black (K). The charging member 2, exposure
member 3, development device 4, and photoreceptor cleaner 7 are
arranged in this order around the photoreceptor 1 along a
rotational direction (indicated by an arrow .alpha.) of the
photoreceptor 1. The intermediate transfer belt 5 is provided below
the photoreceptor 1 and is rotated in a direction indicated by an
arrow .beta.. The primary transfer roller 6 faces the photoreceptor
1 via the intermediate transfer belt 5.
[0049] The secondary transfer roller 8 is arranged at a position on
the intermediate transfer belt 5, and the position is located more
on a downstream side in the rotational direction of the
intermediate transfer belt 5 than the primary transfer roller 6 of
each of the colors is. The secondary transfer roller 8 faces a
predetermined support roller 12 interposing the intermediate
transfer belt 5. The intermediate transfer belt cleaner 9 is
arranged at a position on the intermediate transfer belt 5, and the
position is located more on the downstream side in the rotational
direction of the intermediate transfer belt 5 than a position
facing the secondary transfer roller 8 is.
[0050] Each of the plurality of support rollers 12 is arranged in
parallel to each other, and applies constant tension to the
intermediate transfer belt 5. One support roller 13 out of the
plurality of support rollers 12 is rotationally driven, thereby
rotating the intermediate transfer belt 5. Other support rollers 12
are rotated following the intermediate transfer belt 5. The fixing
member 11 is arranged on a conveyance route TR and located more on
a downstream side than the secondary transfer roller 8 is.
[0051] The photoreceptor 1 carries an electrostatic latent image on
a surface layer thereof. The charging member 2 uniformly charges a
surface of the photoreceptor 1. The exposure member 3 exposes an
image-corresponding part of the surface of the photoreceptor 1 to
form an electrostatic latent image. The development device 4
develops the electrostatic latent image on the surface of the
photoreceptor 1 with charged toner by action of electric field
force. The primary transfer roller 6 transfers, onto the
intermediate transfer belt 5, the toner image formed on the surface
of the photoreceptor 1 by action of electric field force. The
photoreceptor cleaner 7 removes toner (transfer residual toner)
remaining on the surface of the photoreceptor 1.
[0052] Toner images of the respective Y, M, C, and K colors are
transferred to the surface of the intermediate transfer belt 5 in a
superimposed manner, and conveyed to the position facing the
secondary transfer roller 8. On the other hand, a recording medium
T is conveyed to the secondary transfer roller 8 along the
conveyance route TR by a conveyor not illustrated.
[0053] The secondary transfer roller 8 transfers, to the recording
medium T, the toner images of Y, M, C, and K having been
transferred to the surface of the intermediate transfer belt 5 by
action of electric field force. The recording medium T to which the
toner images have been transferred is heated and pressed by the
fixing member 11. Consequently, the toner images are fixed to the
recording medium T. After that, the recording medium T is conveyed
along the conveyance route TR and ejected to the outside of the
image forming apparatus. The intermediate transfer belt cleaner 9
abuts on the intermediate transfer belt 5, and removes (cleans) the
toner (transfer residual toner) remaining on the surface of the
intermediate transfer belt 5.
[0054] The above-described structure of the image forming apparatus
is an example. The constituent elements such as the photoreceptor,
charging member, exposure member, development device, cleaner,
transfer member, and fixing member in the image forming apparatus
may also be used while arbitrarily selecting a known
electrophotographic technique.
[0055] Subsequently, a structure of the photoreceptor cleaner 7 in
the present embodiment will be described.
[0056] FIG. 2 is a cross-sectional view illustrating a structure of
the photoreceptor cleaner 7 according to an embodiment of the
present invention. In FIG. 2, the photoreceptor 1 is illustrated
for convenience of description.
[0057] Referring to FIG. 2, the photoreceptor cleaner 7 includes a
cleaning blade 71, a housing 72, a screw 73, and a toner seal
member 74. The cleaning blade 71 abuts on the photoreceptor 1, and
removes residual toner (transfer residual toner) that is a foreign
matter adhering to the photoreceptor 1. The housing 72 is adapted
to house the residual toner removed by the cleaning blade 71, and
houses the cleaning blade 71 and the screw 73. The screw 73 conveys
the residual toner removed by the cleaning blade 71 to a waste
toner storage box not illustrated. The toner seal member 74
prevents the removed residual toner from being scattered to a
periphery of the photoreceptor 1 by sealing the inside of the
housing 72, and prevents contamination of the surface of the
photoreceptor 1.
[0058] The cleaning blade 71 includes an abutment member 21 that
abuts on the photoreceptor 1, a supporting member 22 that supports
the abutment member 21, and a holding member 23 that holds the
supporting member 22. The holding member 23 is fixed to the housing
72. Since the supporting member 22 acts as a leaf spring, the
abutment member 21 abuts on the photoreceptor 1 with necessary
abutment pressure. With this structure, the transfer residual toner
on the surface of the photoreceptor 1 after primary transfer is
scraped off and removed by the abutment member 21. The abutment
member 21 abuts on the photoreceptor 1 in a direction indicated by
an arrow F1. The abutment member 21 has an abutment function to
abut on the photoreceptor 1. The supporting member 22 has a
supporting function to support the abutment member 21 in the
cleaning blade 71.
[0059] [Structure of Cleaning Blade]
[0060] Subsequently, a structure of the cleaning blade in the
present embodiment will be described.
[0061] FIG. 3 is a top view illustrating the structure of the
cleaning blade 71 according to an embodiment of the present
invention. FIG. 4 is an example of a cross-sectional view taken
along a line Iv-Iv in FIG. 3. In FIGS. 3 and 4, the photoreceptor 1
is illustrated for convenience of description, and the supporting
member 22 is illustrated not in a non-deflected state. Actually,
the supporting member 22 is deflected by force received from the
photoreceptor 1.
[0062] In the following description, an end (right end in FIG. 3)
of the cleaning blade 71 close to the photoreceptor 1 may be
referred to as a leading end, and an end (left end in FIG. 3) of
the cleaning blade 71 far from the photoreceptor 1 in FIG. 3 may be
referred to as a rear end.
[0063] Referring to FIGS. 3 and 4, the abutment member 21 has a
plate-like shape and has a rectangular shape when viewed from
above. The abutment member 21 includes: an upper surface 21a that
is a flat surface; and a lower surface 21b that is a flat surface
located on an opposite side of the upper surface 21a . The abutment
member 21 abuts on the photoreceptor 1 in the vicinity of an edge
that is a boundary between the upper surface 21a and a leading end
211, and the lower surface 21b of the abutment member is supported
by the supporting member 22.
[0064] The abutment member 21 is constituted of an elastic body.
Specifically, the abutment member 21 is made of urethane rubber,
fluoro rubber (FKM), styrene butadiene rubber (SBR), acrylonitrile
butadiene rubber (NBR), or the like. The abutment member 21 is
preferably made of a material excellent in abrasion resistance and
ozone resistance. The abutment member 21 preferably has a thickness
(length in a vertical direction in FIG. 4) of 0.5 mm or more and
2.0 mm or less.
[0065] The abutment member 21 includes an abutment layer 31 and an
adjustment layer 32. The abutment layer 31 abuts on the
photoreceptor 1. The adjustment layer 32 is a part of the abutment
member 21 other than the abutment layer 31. An elongation
percentage of the adjustment layer 32 is larger than an elongation
percentage of the abutment layer 31 in a case where frictional
force is applied from the photoreceptor 1 to the abutment member 21
during rotation of the photoreceptor 1.
[0066] In the present embodiment, the abutment layer 31 and the
adjustment layer 32 are laminated in a predetermined lamination
direction (here, direction perpendicular to an upper surface 22a of
the supporting member 22, namely, the vertical direction in FIG.
4). The adjustment layer 32 is arranged closer to the supporting
member 22 than the abutment layer 31 is, and the adjustment layer
32 is fixed to the supporting member 22 with a bonding agent 24.
The abutment layer 31 is not fixed to the supporting member 22.
Since the adjustment layer 32 is bonded to the supporting member
22, it is possible to suppress unevenness in the abutment pressure
at a position farther from the edge (the boundary between the
leading end 211 and the upper surface 21a ). In a case of defining
a thickness of the abutment layer 31 in the lamination direction as
a thickness t1 and defining a thickness of the adjustment layer 32
in the lamination direction as a thickness t2, it is preferable
that the thickness t1 and t2 have a relation of t1<t2.
[0067] In the present embodiment, since the abutment member 21 is
constituted of the abutment layer 31 and the adjustment layer 32,
the abutting function and the supporting function owned by the
abutment member 21 are exerted by the abutment layer 31 and the
adjustment layer 32 respectively. In other words, the abutment
layer 31 has the edge that abuts on the photoreceptor 1, and has
the abutting function to abut on the photoreceptor 1. The abutting
function includes: a cleaning property to block the residual toner
with the edge; abrasion resistance to perform cleaning for a long
period of time; a function to abut on the photoreceptor 1 without
damaging the photoreceptor 1; and the like. The adjustment layer 32
has an adjustment function to suppress unevenness in the abutment
pressure of the cleaning blade 71 to the photoreceptor 1.
[0068] A length W1 of the abutment member 21 (length in the
rotational axis direction of the photoreceptor 1) along a
longitudinal direction of the cleaning blade 71 (direction
indicated by an arrow LG in FIG. 3) is longer than a length W2 of
an image forming region of the photoreceptor 1. In a case where the
cleaning blade 71 is molded with a metal mold, the thickness and
the length W1 of the abutment member 21 may be smaller than the
above-mentioned ranges. The length of the abutment member 21 along
a short direction of the cleaning blade 71 (direction indicated by
an arrow PR in FIG. 3) is preferably 5 mm or more and 10 mm or
less.
[0069] The abutment member 21 may be fixed to the supporting member
22 also with a double-sided tape or the like. From the viewpoint of
securing straightness of the supporting member 22, it is preferable
that the abutment member 21 be fixed to the supporting member 22
with the bonding agent 24. As the bonding agent 24, a thermoplastic
bonding agent is preferable. Additionally, the abutment member 21
may be fixed to the supporting member 22 also by pouring a molten
material of the abutment member 21 into a metal mold in a state in
which the supporting member 22 is fixed to the metal mold of the
abutment member 21 at the time of molding the abutment member 21.
In this case, the bonding agent or the double-sided tape becomes
unnecessary.
[0070] A position of the leading end 211 of the abutment member 21
preferably coincides with a position of a leading end 221 of the
supporting member 22. In a case where the leading end 221 of the
supporting member 22 protrudes more than the leading end 211 of the
abutment member 21, the supporting member 22 preferably does not
contact the photoreceptor 1. In a case where the leading end 211 of
the abutment member 21 protrudes more than the leading end 221 of
the supporting member 22, a protruding length of the abutment
member 21 is preferably 0.5 mm or less. With this structure, it is
possible to prevent a situation in which the abutment member 21
protruding from the leading end 221 of the supporting member 22 is
deformed and the abutment pressure on the photoreceptor 1 is
decreased with time.
[0071] The supporting member 22 is plate-like shape and has a
rectangular shape when viewed from above. The supporting member 22
includes a protrusion PR protruding toward the leading end side
from the holding member 23 (protruding in the short direction of
the cleaning blade 71). The protrusion PR protrudes from the
holding member 23 in a direction opposite to the rotational
direction of the photoreceptor 1 (direction indicated by the arrow
.alpha.). The abutment member 21 is fixed to the leading end 221 of
the supporting member 22. The supporting member 22 includes: the
upper surface 22a (exemplary first supporting member surface)
located on the edge side of the abutment member 21 (position where
the abutment member 21 abuts on the photoreceptor 1); and a lower
surface 22b (exemplary second supporting member surface) located on
an opposite side of the upper surface 22a and facing an upper
surface 23a of the holding member 23. The abutment member 21 is
fixed to the upper surface 22a of the supporting member 22.
[0072] The supporting member 22 is constituted of a metallic leaf
spring or the like. Specifically, the supporting member 22 is made
of stainless steel or phosphor bronze having high corrosion
resistance. Particularly, the stainless steel is preferable because
the stainless steel has high strength and high fatigue
strength.
[0073] The supporting member 22 preferably has a thickness (length
in the vertical direction in FIG. 4) that is larger than 0 and 100
.mu.m or less in order to ensure good followability relative to
rotation of the photoreceptor 1. Additionally, the supporting
member 22 preferably has a Young's modulus of 98 GPa or more and
206 GPa or less. It is preferable that the structure of the
supporting member 22 be selected in consideration of the
above-described thickness and Young's modulus.
[0074] The holding member 23 holds a part of a rear end side of the
supporting member. The holding member 23 has the upper surface 23a
(exemplary first holding member surface) located on the edge side
of the abutment member 21; and a lower surface 23b (exemplary
second holding member surface) that is a flat surface located on an
opposite side of the upper surface 23a.
[0075] The supporting member 22 is fixed to the upper surface 23a
of the holding member 23 by a method such as welding, bonding,
fastening with a screw, or the like. Here, the structure in which
the supporting member 22 is fixed to the holding member 23 by spot
welding is illustrated, and a welded part (a position where the
supporting member 22 and the holding member 23 are melted and
fixed) 25 is located between the supporting member 22 and the
holding member 23.
[0076] The holding member 23 is constituted of a metal (sheet
metal) or the like. Specifically, the holding member 23 is
constituted of a steel plate such as steel electrically chromate
coated (SECC). Preferably, the holding member 23 has a thickness of
1.6 mm or more and 2.0 mm or less in order to: suppress deformation
of the holding member 23 caused by pressure applied to the cleaning
blade 71, external force, and the like; and ensure the high edge
straightness of the cleaning blade 71.
[0077] A distance between the photoreceptor 1 and the abutment
member 21 is determined by a position where the cleaning blade 71
is fixed to the housing 72 and an angle of the cleaning blade 71
with respect to the housing 72. Additionally, a free length of the
cleaning blade 71 is determined by a position where the supporting
member 22 is installed at the holding member 23. Furthermore, a
deflection amount of the supporting member 22 is determined by the
position where the cleaning blade 71 is fixed to the housing
72.
Effects of Embodiment
[0078] Next, effects of the cleaning blade 71 in the present
embodiment will be described.
[0079] FIG. 5 is a cross-sectional view illustrating a structure of
a cleaning blade 1071a in a first comparative example. FIG. 6 is a
view illustrating the structure of the cleaning blade 1071a when
viewed from a direction indicated by an arrow V in FIG. 5. Note
that, in FIG. 6, unevenness in a height H of the cleaning blade
1071a is illustrated in a manner more emphasized than an actual
state.
[0080] Referring to FIGS. 5 and 6, the cleaning blade 1071a in the
first comparative example differs from the cleaning blade 71 of the
present embodiment in that an abutment member 21 includes only one
layer (here, the layer having material quality same as material
quality of an adjustment layer 32).
[0081] The unevenness in the height H of the cleaning blade 1071a
is caused as illustrated in FIG. 6 by a state of a bonding agent 24
to bond the abutment member 21 to a supporting member 22, a bonding
method at the time of bonding, and the like. When the height H
becomes uneven, the abutment pressure is increased in a region
where the height H is high, and the abutment pressure is decreased
in a region where the height H is low in a case where the abutment
member 21 abuts on a photoreceptor 1. As a result, unevenness in
the abutment pressure causes non-uniformity in a wear amount of the
photoreceptor 1, and density becomes non-uniform in a printed image
Additionally, the abutment pressure is decreased in the region
where the height H is low, thereby causing cleaning failure. The
problem can be suppressed to some extent by improving bonding
accuracy between the abutment member 21 and the supporting member
22, but the problem can be hardly solved completely.
[0082] FIG. 7 is a view schematically illustrating a pulled amount
of an edge of the abutment member 21 in the cleaning blade 1071a of
the first comparative example.
[0083] Referring to FIG. 7, the unevenness in the height H of the
cleaning blade 1071a is not caused only by bonding but also by
fixation of the abutment member 21 to the supporting member 22
despite a fact that the abutment member 21 and the supporting
member 22 have different kinds of material quality. As an example,
in a case where the supporting member 22 is constituted of a
metallic leaf spring, the supporting member 22 has flexibility, but
a deflection direction of the supporting member 22 is only a
direction opposite to a direction indicated by an arrow F1
(direction in which the abutment pressure is applied to the
photoreceptor 1). The supporting member 22 is not deflected in the
direction indicated by an arrow F2 (rotational direction of the
photoreceptor 1) and exhibits a characteristic of a substantially
rigid body.
[0084] When the photoreceptor 1 is rotated, frictional force in the
direction indicated by the arrow F2 is applied to the cleaning
blade 1071a , and the edge of the abutment member 21 (position
abutting on the photoreceptor 1) is pulled from a position P2 to a
position P3. As described above, the supporting member 22 is hardly
deflected by the frictional force. Additionally, since the abutment
member 21 is fixed to the supporting member 22, and a position P1
at an end on a leading end side of the abutment member 21 is
restrained by the supporting member 22. Therefore, the pulled
amount of the edge of the abutment member 21 (a distance from the
position P2 to the position P3) by rotation of the photoreceptor 1
is small.
[0085] When the pulled amount of the edge of the abutment member 21
by rotation of the photoreceptor 1 is small, an effect of
suppressing (leveling) the unevenness in the abutment pressure is
small. In other words, assuming that the unevenness in the height H
of the cleaning blade 1071a is constant, when the pulled amount of
the edge is large, a proportion of the unevenness in the height H
relative to the pulled amount of the edge becomes low and the
unevenness in the abutment pressure can be leveled by the pulled
amount of the edge, however; when the pulled amount of the edge is
small, a proportion of the unevenness in the height H relative to
the pulled amount of the edge becomes high and the unevenness in
the abutment pressure cannot be leveled by the pulled amount of the
edge.
[0086] FIG. 8 is a cross-sectional view illustrating a structure of
a cleaning blade 1071b in a second comparative example.
[0087] Referring to FIG. 8, the cleaning blade 1071b in the second
comparative example differs from the cleaning blade 71 of the
present embodiment in that an abutment member 21 is not supported
by a supporting member and includes only one layer (here, the layer
having material quality same as material quality of an adjustment
layer 32).
[0088] When the photoreceptor 1 is rotated, frictional force in a
direction indicated by an arrow F2 is applied to the cleaning blade
1071b , and an edge of the abutment member 21 (position abutting on
the photoreceptor 1) is pulled from a position P2 to a position P4.
In the cleaning blade 1071b , since the abutment member 21 is not
restrained by the supporting member, the pulled amount of the edge
of the abutment member 21 (distance from the position P2 to the
position P4) by rotation of the photoreceptor 1 is large.
Therefore, even when a height H of the cleaning blade 1071b is
uneven, unevenness in abutment pressure is leveled. Accordingly,
the unevenness in the abutment pressure in a longitudinal direction
of the cleaning blade is a problem peculiar to the cleaning blade
in which the abutment member 21 is supported by the supporting
member 22. Meanwhile, in the cleaning blade 1071b , there is a
problem that permanent distortion tends to occur in the cleaning
blade because the abutment member 21 is not supported by the
supporting member.
[0089] FIG. 9 is a view schematically illustrating a pulled amount
of an edge of an abutment member 21 in a cleaning blade 1071c of a
third comparative example. FIG. 10 is an enlarged view of an edge
of the abutment member 21 in the cleaning blade 1071c illustrated
in FIG. 9.
[0090] Referring to FIGS. 9 and 10, the cleaning blade 1071c in the
third comparative example differs from the cleaning blade 71 of the
present embodiment in that the abutment member 21 includes only one
layer (here, the layer having material quality same as material
quality of an abutment layer 31). In other words, the cleaning
blade 1071c is obtained by using, as the abutment member 21, a
material that can be easily elongated in a conventional cleaning
blade in which the abutment member 21 is supported by a supporting
member 22.
[0091] According to the cleaning blade 1071c , an edge of the
abutment member 21 is pulled from a position P2 to a position P5 by
rotation of a photoreceptor 1, and the pulled amount of the edge of
the abutment member 21 (distance from a position P2 to a position
P5) by rotation of the photoreceptor 1 can be increased. As a
result, even when a height H of the cleaning blade 1071c becomes
uneven, unevenness in abutment pressure can be leveled.
[0092] On the other hand, the cleaning blade 1071c has the
following problem. In the cleaning blade 1071c , in a case where
frictional force is applied from the photoreceptor 1 to the
abutment member 21 during rotation of the photoreceptor 1, a large
load is applied to the entire abutment member 21, and a deformation
amount of the abutment member 21 is increased. Consequently,
fatigue is accumulated in the abutment member 21 as the number of
printed sheets is increased, and the edge of the abutment member 21
is likely to be cracked or fractured. As a result, the life of the
abutment member 21 is shortened.
[0093] FIG. 11 is a view schematically illustrating the pulled
amount of the cleaning blade 71 according to the embodiment of the
present invention. FIG. 12 is an enlarged view of the edge of the
abutment member 21 in the cleaning blade 71 illustrated in FIG.
11.
[0094] Referring to FIGS. 11 and 12, in the cleaning blade 71
according to the present embodiment, unevenness in abutment
pressure caused by unevenness in the height H is suppressed by the
adjustment layer 32. In other words, an elongation percentage of
the adjustment layer 32 is larger than an elongation percentage of
the abutment layer 31 in a case where frictional force is applied
from the photoreceptor 1 to the abutment member 21 during rotation
of the photoreceptor 1. Therefore, even when the adjustment layer
32 is restrained by the supporting member 22 at a position P1, the
adjustment layer 32 can be elongated by a sufficient length. The
edge of the abutment member 21 is pulled from a position P2 to a
position P6 by rotation of the photoreceptor 1, and the pulled
amount of the edge of the abutment member 21 (distance from the
position P2 to the position P6) by rotation of the photoreceptor 1
can be increased. As a result, even when the height H of the
cleaning blade 71 is uneven, the unevenness in the abutment
pressure can be suppressed. Additionally, since the unevenness in
the abutment pressure is suppressed, non-uniformity in density and
cleaning failure caused by non-uniformity in wear of the
photoreceptor 1 can be suppressed. Furthermore, since the
elongation percentage of the abutment layer 31 is small, it is
possible to suppress crack and fracture of the edge of the abutment
member 21 caused by accumulation of fatigue in the abutment layer
31. As a result, the life of the abutment member 21 can be
improved. Furthermore, since the abutment member 21 is supported by
the supporting member 22 that is the separate member, permanent
distortion of the cleaning blade 71 can be suppressed.
[0095] Particularly, since the thickness t2 in the lamination
direction of the adjustment layer 32 is thicker than the thickness
t1 in the lamination direction of the abutment layer 31 as
illustrated in FIG. 4, an easily-elongated region in the abutment
member 21 is increased, and therefore, the unevenness in the
abutment pressure can be effectively suppressed.
[0096] [Characteristics of Abutment Layer and Adjustment Layer]
[0097] Next, characteristics of the abutment layer and the
adjustment layer in the present embodiment will be described.
[0098] FIG. 13 is a graph illustrating respective stress-strain
(SS) characteristics of the abutment layer 31 and the adjustment
layer 32 and elongation percentages EL1 and EL2 in a case where
stress ST1 is applied in the embodiment of the present invention.
Note that a line L1 represents the SS characteristic of the
abutment layer 31, and a line L2 represents the SS characteristic
of the adjustment layer 32 in FIGS. 13 to 16.
[0099] Referring to FIG. 13, in a case where frictional force is
applied from the photoreceptor 1 to the abutment member 21 during
rotation of photoreceptor 1, the stress ST1 is applied to the
abutment member 21. The elongation percentage EL2 of the adjustment
layer 32 in the case where the stress ST1 is applied is larger than
the elongation percentage EL1 of the abutment layer 31. The stress
ST1 is normally several MPa although the stress is changed by
specifications, a use state, a use environment, and the like of the
cleaning blade 71.
[0100] FIG. 14 is a graph illustrating the respective SS
characteristics of the abutment layer 31 and the adjustment layer
32 and integrated values Si and S2 of tensile stress required to
elongate a length with an elongation percentage 0% to a length with
an elongation percentage 100% in the embodiment of the present
invention.
[0101] Referring to FIG. 14, the integrated value S2 of the tensile
stress required to elongate the adjustment layer 32 from the length
with the elongation percentage 0% to the length with the elongation
percentage 100% is preferably lower than the integrated value Si of
the tensile stress required to elongate the abutment layer 31 from
the length with the elongation percentage 0% to the length with the
elongation percentage 100% With these integrated values, the
adjustment layer 32 is more easily elongated than the abutment
layer 31 within a range of 0 to 100% that is the range of normal
elongation percentage.
[0102] FIG. 15 is a graph illustrating the respective SS
characteristics of the abutment layer 31 and the adjustment layer
32 and 200% moduli M11 and M12 in the embodiment of the present
invention.
[0103] Referring to FIG. 15, the 200% modulus represents force
required to elongate a material from a length with an elongation
percentage 0% to a length of an elongation percentage 200%. The
200% modulus M12 of the adjustment layer 32 is preferably lower
than the 200% modulus M11 of the abutment layer 31. In the event of
abnormality, strong force may be locally or entirely applied to the
abutment member 21. Since the 200% moduli M11 and M12 of the
abutment layer 31 and the adjustment layer 32 have the
above-described relation, in the case where strong force is applied
to the abutment member 21, it is possible to prevent a situation in
which the elongation percentage of the abutment layer 31 becomes
larger than the elongation percentage of the adjustment layer 32
(situation in which the adjustment layer 32 has a characteristic as
indicated by a line L3 in FIG. 15), and furthermore, it is possible
to suppress crack and fracture of the edge of the abutment member
21 caused by accumulation of fatigue in the abutment layer 31.
[0104] FIG. 16 is a graph illustrating the respective SS
characteristics of the abutment layer 31 and the adjustment layer
32 and elongation after fracture BL1 and elongation after fracture
BL2 in the embodiment of the present invention.
[0105] Referring to FIG. 16, it is preferable that the elongation
after fracture BL1 of abutment layer 31 is larger than the
elongation after fracture BL2 of adjustment layer 32. The
elongation after fracture is an elongation percentage when a
material is fractured, and differs from ease of elongation. In the
case where strong force is applied to the abutment member 21,
mainly the adjustment layer 32 is elongated and a load applied to
the abutment layer 31 is reduced in the present embodiment. Since
the elongation after fracture BL1 of the abutment layer 31 and
elongation after fracture BL2 of the adjustment layer 32 have the
above-described relation, tensile strength of the abutment layer 31
becomes stronger and the abutment layer 31 is hardly fractured even
in the case where the strong force is applied to the abutment
member 21.
FIRST PRACTICAL EXAMPLE
[0106] The inventor of the present application conducted following
tests to evaluate performance of the cleaning blade of the present
invention.
[0107] FIG. 17 is a table illustrating structures and verification
results of Examples 1 to 5 of the present invention in a first
practical example of the present invention and Comparative Examples
1 to 5. FIG. 18 is a table illustrating various conditions in the
first practical example of the present invention.
[0108] Referring to FIGS. 17 and 18, ten types of cleaning blades
including Examples 1 to 5 of the present invention and Comparative
Examples 1 to 5 were prepared, and verifications 1 to 5 were
conducted. Each of Examples 1 to 5 of the present invention had the
structure illustrated in FIG. 4 and was an example in which an
adjustment layer had an elongation percentage larger than an
elongation percentage of an abutment layer relative to same force.
Comparative Examples 1 and 2 were examples in which an adjustment
layer had an elongation percentage smaller than an elongation
percentage of an abutment layer relative to same force. Each of
Comparative Examples 3 and 4 had the structure illustrated in FIG.
5, and was an example in which an abutment member including only
one layer was supported by a supporting member. Comparative Example
5 had the structure illustrated in FIG. 8, and was an example
(conventional cleaning blade made of only urethane rubber) in which
an abutment member was not supported by a supporting member. A free
length of the abutment member in Comparative Example 5 is 10
mm.
[0109] A drum unit (unit including a photoreceptor) in an MFP
having a product name "bizhub C284e" manufactured by Konica Minolta
was prepared. Additionally, as a cleaning blade of a photoreceptor
cleaner of this drum unit, each of the above-described ten types of
cleaning blades was used. In the verification 2, an organic
photoreceptor not including a high-hardness protective layer for
the purpose of long life was used as a photoreceptor of the drum
unit in order to accurately evaluate non-uniformity in wear. Other
conditions in the tests were shown in FIG. 18. Note that the free
length in FIG. 18 is a distance from a position to be a fulcrum of
deformation of the supporting member in the holding member to a
leading end of the abutment member fixed to the supporting
member.
[0110] For each of the above-described ten types of cleaning
blades, five verifications shown in FIG. 17 were conducted.
[0111] The verification 1 was a pulled amount measurement. In the
verification 1, each of the cleaning blades was installed in the
drum unit in which a friction coefficient was set at a constant
value. The photoreceptor was driven at a speed of 165 mm/s, and
then a moved distance from an abutment position during a stopped
state was measured by photographing an abutment position between
the cleaning blade and the photoreceptor with a camera from the
extending direction of the rotational shaft of the photoreceptor
being currently driven, and the measured value is determined as a
pulled amount.
[0112] In the case where the pulled amount was extremely large (in
a case of being equivalent to a pulled amount of the conventional
cleaning blade made of only urethane in FIG. 8), specifically, in a
case where the pulled amount was 100 .mu.m or more), evaluation was
"excellent (A)", in a case where the pulled amount was large (in a
case of being larger a pulled amount of the cleaning blade (FIG. 5)
in which the conventional abutment member including only one layer
was supported by the supporting member), evaluation was "good (B)",
and in a case where a pulled amount was small (in a case of being
almost equivalent to the pulled amount of the cleaning blade (FIG.
5) in which the conventional abutment member including only one
layer was supported by the supporting member), evaluation was "poor
(F)".
[0113] As results of the verification 1, evaluation was "A" or "B"
in all of all of Examples 1 to 5 of the present invention. In
Comparative Example 4, evaluation was "A" because the abutment
member made of a material easily elongated was adopted. In
Comparative Example 5, the pulled amount was increased to 152 .mu.m
(about 120 .mu.m depending on a condition) and evaluation was "A"
because the abutment member was not supported by the supporting
member. On the other hand, in Comparative Examples 1 and 2, since
the abutment member was made of a material that can be hardly
elongated, the pulled amount was small like approximately 50 .mu.m
that was almost equivalent to a pulled amount of the cleaning blade
(Comparative Example 3) in which the conventional abutment member
including only one layer was supported by the supporting
member.
[0114] The verification 2 was evaluation on non-uniformity in wear.
In the verifications 2 to 4, durability test was conducted in
advance by printing characters and image charts with a print
percentage of 5% on one hundred thousand pieces of sheets in an
intermittent mode in a normal environment (temperature 23.degree.
C. and humidity 65%).
[0115] In the verification 2, a wear amount in a region having a
length of 10 mm in the longitudinal direction of the photoreceptor
was measured after the above durability test. In a case where a
difference in the wear amount (wear difference) in this region was
less than 3 .mu.m, evaluation was "B", and in a case where
difference was 3 .mu.m or more, evaluation was "F". The reason was
that: when the difference of 3 .mu.m or more is generated in the
region having the length of 10 mm in the longitudinal direction of
the photoreceptor, non-uniformity in density was visually confirmed
in a printed image.
[0116] As a result of the verification 2, evaluation was "A" in all
of Examples 1 to 5 of the present invention. In Comparative Example
4 also, evaluation was "B" because of the large pulled amount.
Meanwhile, in Comparative Example 5, evaluation was "B" because the
abutment member was not supported by the supporting member, and
there was no problem of non-uniformity in wear. On the other hand,
in Comparative Examples 1 to 3, evaluation was "F" because the
pulled amount was small.
[0117] The verification 3 was evaluation on cleaning performance.
In the verification 3, a cleaning blade was taken out from the drum
unit after the durability test, and was installed in a new drum
unit. A large amount of residual toner was made to adhere onto
(remain on) the photoreceptor by developing an image with a print
percentage of 100% on the photoreceptor and performing printing
while suppressing a transfer rate onto the intermediate transfer
belt in an environment having a low temperature and a low humidity
(temperature of 10.degree. C. and humidity of 15%). An amount of
the toner adhering to the photoreceptor was changed in a range of 0
to 3 g/m.sup.2. An image printed on a sheet was visually checked.
In a case where no streak appears due to incomplete wiping by the
cleaning blade, evaluation was "B", and in a case where a streak
appears due to incomplete wiping by the cleaning blade, evaluation
was "F".
[0118] As a result of the verification 3, evaluation was "B" in all
of Examples 1 to 5 of the present invention. Evaluation was "F" in
all of Comparative Examples 1 to 5. Particularly, in Comparative
Examples 1 to 3, the streaks appeared due to incomplete wiping at a
position included in an image and corresponding to a region where
the abutment pressure of the cleaning blade applied to the
photoreceptor was decreased due to unevenness in the abutment
pressure. In Comparative Example 4, the edge of the abutment member
was damaged, and a streak due to incomplete wiping appeared at a
position included in an image corresponding to a region where the
edge was damaged. In Comparative Example 5, a streak due to
incomplete wiping by the cleaning blade appeared in an entire image
because the abutment pressure of the cleaning blade applied to the
photoreceptor was decreased due to a damage at the edge of the
abutment member and permanent distortion of the abutment
member.
[0119] The verification 4 was evaluation on presence/absence of a
damage of the cleaning blade under severe conditions. In the
verification 4, an additional durability test was conducted under
more severe conditions after the above durability test, and the
presence/absence of a damage at a leading end of each cleaning
blade (leading end of each abutment member) was evaluated. In the
additional durability test, printing was performed on fifty
thousand pieces of sheets while increasing the number of
intermittent times in an environment having a low temperature and a
low humidity (temperature 10.degree. C. and humidity 15%) and an
environment having a high temperature and a high humidity
(temperature 30.degree. C. and humidity 85%). In a case where the
leading end of the cleaning blade was not damaged by only normal
abrasion after the additional durability test, evaluation was "B",
in a case where the leading end of the cleaning blade was not
damaged after the durability test and the leading end of the
cleaning blade was damaged after the additional test, evaluation
was "fair (C)", and in a case where the leading end of the cleaning
blade was damaged before the additional durability test, evaluation
is provided as "F".
[0120] As a result of the verification 4, evaluation was "B" in
Examples 1, 4, and 5 of the present invention. In Examples 2 and 3
of the present invention, evaluation was "C" because elongation
after fracture of the abutment layer was smaller than elongation
after fracture of the adjustment layer. The elongation after
fracture was elongation at the time of damage, and it was found
that: when the elongation after fracture of the abutment layer was
small, the edge of the abutment layer was damaged under the severe
conditions. In Comparative Examples 1 to 3, evaluation was "B". In
Comparative Examples 4 and 5, evaluation was "F", and the edge of
the abutment member was already damaged before conducting the
additional durability test.
[0121] The verification 5 was evaluation on permanent distortion.
In the verification 5, the cleaning blade was installed in the drum
unit under setting conditions illustrated in FIG. 18, and the
cleaning blade was left for 1000 hours in an environment having a
high temperature and a high humidity (temperature 30.degree. C. and
humidity 85%). After being left for the mentioned period, the
abutment pressure of the cleaning blade to the photoreceptor was
measured, and a decreased amount of the abutment pressure during a
period before and after being left was calculated. In a case where
the decreased amount of the abutment pressure was smaller than a
predetermined value, evaluation was "B", and in a case where the
decreased amount of the abutment pressure was larger than the
predetermined value, evaluation was "F".
[0122] As a result of the verification 5, there was no permanent
distortion and evaluation was "B" in Examples 1 to 5 of the present
invention and Comparative Examples 1 to 4 because the abutment
member was supported by the supporting member. In Comparative
Example 5, evaluation was "F" because the abutment member was not
supported by the supporting member. From the above, it was found
that there was no permanent distortion and the abutment pressure
was not decreased because the abutment member was supported by the
supporting member.
[0123] Meanwhile, referring the results of Examples 1 and 2 of the
present invention, it was found that hardness and a Young's modulus
of each of the abutment layer and the adjustment layer hardly
affected the results of verifications 1 to 3.
SECOND PRACTICAL EXAMPLE
[0124] The inventor of the present application conducted following
tests to evaluate performance of the cleaning blade of the present
invention.
[0125] FIG. 19 is a graph illustrating a relation between a value
of (t2.times.M1)/(t1.times.M2) and a pulled amount in a second
practical example of the present invention.
[0126] Referring to FIG. 19, in a case of defining a thickness that
is a length of the abutment layer in the lamination direction as a
thickness t1, defining a thickness that is a length of the
adjustment layer in the lamination direction of the adjusting layer
as a thickness t2, defining a 100% modulus of the abutment layer as
a modulus M1, and defining a 100% modulus of the adjustment layer
as a modulus M2, many cleaning blades having different values of
(t2.times.M1)/(t1.times.M2) were prepared. All of the prepared
cleaning blades were examples of the present invention (having the
structure illustrated in FIG. 4, in which the adjustment layer had
an elongation percentage larger than an elongation percentage of
the abutment layer relative to the same force). For each of the
prepared cleaning blades, a pulled amount was measured in a method
similar to that in the verification 1 of the first practical
example.
[0127] When a value of (t2.times.M1)/(t1.times.M2) was larger than
3 as a result of measurement of a pulled amount, the pulled amount
was particularly large, and an effect of suppressing unevenness in
the abutment pressure was higher.
[0128] [Modified Examples of Cleaning Blade]
[0129] FIGS. 20A to 20D are cross-sectional views illustrating
structures of modified examples of the cleaning blade 71 according
to the embodiment of the present invention.
[0130] Referring to FIGS. 20A to 20D, the abutment member 21 of the
cleaning blade 71 of the present embodiment may have following
structures besides the structure illustrated in FIG. 4. In the
abutment member 21 illustrated in FIG. 20A, both of the abutment
layer 31 and the adjustment layer 32 are fixed to the supporting
member 22, and the abutment layer 31 surrounds an upper surface and
a part of side surfaces of the adjustment layer 32. The adjustment
layer 32 is provided only in the vicinity of a position P1 of an
end on the leading end side of the abutment member 21.
[0131] In the abutment member 21 illustrated in FIG. 20B, the
adjustment layer 32 constitutes a part of the upper surface 21a of
the abutment member 21 and surrounds a lower surface and a part of
side surfaces of the abutment layer 31. The abutment layer 31 is
provided only in the vicinity of the edge of the abutment member
21.
[0132] In the abutment member 21 illustrated in FIG. 20C, the
abutment layer 31 and the adjustment layer 32 are laminated in a
direction inclined with respect to the upper surface 22a of the
supporting member 22 (direction from lower left to an upper right
in FIGS. 20A to 20D).
[0133] The abutment member 21 illustrated in FIG. 20D further
includes an underlayer 33 in addition to the abutment layer 31 and
the adjustment layer 32. The underlayer 33 is fixed to the
supporting member 22. The adjustment layer 32 is provided on an
upper surface of the underlayer 33 and is not fixed to the
supporting member 22.
[0134] [Others]
[0135] A relation between hardness of the abutment layer 31 and
hardness of the adjustment layer 32 is arbitrary. In a case where
the hardness of the adjustment layer 32 is lower than the hardness
of the abutment layer 31, unevenness in the height of the abutment
member 21 can be easily reduced at the time of fixing the abutment
member 21 by using a bonding agent. In a case where the hardness of
the abutment layer 31 is lower than the hardness of the adjustment
layer 32, abrasion resistance of the abutment member 21 can be
improved. Similarly, a relation between a Young's modulus of the
abutment layer 31 and a Young's modulus of the adjustment layer 32
is arbitrary.
[0136] The cleaning blade 71 in the above-described embodiment may
be mounted not only on the photoreceptor cleaner 7 that removes a
matter adhering to the photoreceptor 1, and may also be mounted on
the intermediate transfer belt cleaner 9 that removes a matter
adhering to the intermediate transfer belt 5.
[0137] Although embodiments and practical examples of the present
invention have been described and illustrated in detail, it should
be considered that the disclosed embodiments and practical examples
are made for purposes of illustration and example only and not
limitation in all respects. The scope of the present invention
should be interpreted not by the above description but by terms of
the appended claims, and is intended to include meanings equivalent
to the scope of claims as well as all of changes within the scope
of the claims
* * * * *